Validation in another controller - You have 2 controllers, posts and comments, you want to be able to have a form on a posts view which submits to the comments controller, which does its thing then redirect to referrer - easy!

ConditionalValidation behavior - The validations in cake 1.2 are great, but sometimes I needed to have conditional validation. Because the validations are set at model level, i did implement a behavior that allows to turn on or off validation.